Two players share a three-card deck: Jack, Queen, and King. The highest card wins. You each ante one chip. You each get a card. The third card remains unseen. The first player can check or bet one chip. Player two can call, fold, check, or raise one. If needed, player one can then call or fold (no reraising).
Obviously, if you’re confronted by a bet, there’s no reason to call with a Jack and no reason to fold with a King. But what do you do if you’re holding a Queen and playing first?